\[P(0.5 \leq X_1 \leq 1.5 \text{ and } 0 \leq X_2 \leq 1) = \int_{0.5}^{1.5} \int_{0}^1 f(x_1, x_2 | \mathbf{\mu}, \Sigma) \, d x_2 d x_1\]